Human Hibernation and Suspended Animation

As far as we know, time travel into the future is not possible. Well, technically, we do it all the time, we just can’t do it any faster. In many ways time is the enemy of humanity, thanks to our relatively short life spans. Until we can figure out how to extend our lives, one of the few realistic ways to endure long bouts of time may be with the use of suspended animation or hibernation.

What is Suspended Animation?

As living organisms we are an ongoing chemical reaction. That’s what we refer to as our “metabolism”. It’s the process of taking in energy from the environment around us and using it to sustain our form and existence. When we die, those chemical processes are halted. We stop maintaining life functions, and decomposition begins. Our brains very quickly become irreparably disintegrated and that which makes us conscious, our minds, is gone forever. If you are lucky, you may sustain your life for about a century. The very oldest humans have lived for nearly 120 years.

There are many reasons why we only last this long. Much of it is intentional. We are genetically programmed to age and die so that we do not compete with the next generation and overpopulate the world. Some of what eventually does us in is simply damage that accumulates over the course of life. The act of breathing, the extraction of oxygen for energy, is also a process that slowly kills us. The radiation that permeates the universe can damage our genes, causing problems such as cancer, or we can just be slowly poisoned by various things.

Until we can fix all the various causes for a human life to end, we could use the technique of suspended animation to put a pause to all of that. Simply put, suspended animation means slowing down or even stopping those life processes, without death or decomposition.

What, Like a Bear?

There are plenty of animals who naturally have the ability to slow down their metabolisms so that they can get around shortages in food or bad environmental conditions that are hard to survive. Basically, when a bear goes to sleep for the winter, its body cuts all energy needs by a huge margin. Black bears, for example, sleep for six months without any food or water. While they are hibernating their heart rates slow down from 55 beats per minutes to 14. That’s a 75% reduction.

Bears are far from the only animal to have the luxury of putting life on pause. The common box turtle will slow its heart down to one beat every five to ten minutes! It can keep this up for 154 days – all without ever taking a breath; the only oxygen the turtle will take in is through its skin.

There are also a number of animals (such as certain fish) that can survive outright freezing with successful reanimation upon thawing.

Hibernation, a Lost Part of History

As mammals ourselves, hibernation is most likely a part of our genetic history. However, as you no doubt know, humans do not hibernate. For some time now scientists have tried to induce hibernation in humans in various ways. There are more than a few accounts of humans going into something that seems similar to hibernation. Mainly, these stories relate to severe cold. People who have “died” in the snow or by falling into icy water have been revived hours later, despite their heart and lungs doing nothing while they were under. The lowered temperatures drastically reduce their oxygen requirements, preventing brain damage.

Medical Miracles

Today we’re seeing cold-induced suspended animation actually used to save trauma patients. Let’s say that someone comes into the emergency room with a gunshot wound. On a mechanical level the surgeon is perfectly capable of repairing the damage, but the patient is losing blood faster than medics can provide. A lack of blood means a lack of oxygen and, starved of oxygen, the brain has five or so minutes before it’s too late. Using suspended animation induced through cold extends that time long enough so that the physical damage can be repaired.

The technique is called “EPR”, or emergency preservation and resuscitation. It may one day be a standard method for saving lives. It may spell the end of death en route to the hospital for trauma patients or those who have suffered a stroke or heart attack. EPR trials have shown that a patient can be suspended for up to an hour with no blood, pulse, or brain activity. Patients who would have been impossible to save before can now be returned to life. It’s almost a miracle of modern medicine.

Hibernate in Ice

This short-term suspended animation is obviously incredibly useful, but it’s nothing like those of animals that can stick it out on little energy or oxygen for months. If humans could achieve that, it would open up many possibilities.

One area that still relates to cold is cryogenics. This is a process where a person is not just chilled, but frozen. They are frozen in such a way so that cellular damage is limited. The idea is that medical science will one day advance to the point where a body can be thawed and brought back, using regenerative medicine that simply doesn’t exist today. Obviously, cryogenic preservation is something we only do to people who have already been declared dead under current medical parameters. Since we don’t yet have any way of reversing the freezing process safely, cryogenic freezing of a living person is basically murder.

Reaching for the Stars

In the future, we may use nanotechnology and regenerative medicine to bring people back from the deep freeze, but for now it would be good enough to drastically, safely slow down metabolisms for long stretches. Space travel is one of the primary uses for this technology. If you want to send living human bodies on trips that might take decades or centuries, this is a way to do it without the traveler needing impossible amounts of food or air – not to mention the fact that you want people alive and well at the other end of the trip. Putting people in suspended animation on an affordable ship is a better prospect than the idea of massive, multi-generational arkships.

Human Problems

While suspended animation is a laudable dream, there are still many problems to overcome. For one thing, keeping people in good shape while they lay motionless for months or years is not a simple issue. Without the right stimulation and waste processing, muscle and bone can degrade very quickly. Just being in microgravity wreaks havoc on the bodies of astronauts. We still need to learn a lot about the fine biochemical adaptations that hibernating animals have. It’s not a directly-transferable trait.

It may well be that we’ll have to use genetic engineering to imbue human space travelers with the ability to hibernate. In the end, if this is a trait that humanity can really put to use on Earth or beyond, we may have to build it into ourselves.